Fix doc path in Makefile so it does not contain version
Drop the make deb target

Debuild will fail if the patch is already part of upstream source.
OTOH, its useless if it is only added via the debian patch.

To build, use:

make build
mv pkg/chruby-x.y.z.tar.gz ../chruby_x.y.z.orig.tar.gz
debuild